Foldable lift device



Dec. 7, 1965 s. w. SCHNEIDER 3,

FOLDABLE LIFT DEVICE Filed Dec. 23. 1963 2 heets-Sheet 1 //v VE/V ToA BERN/0L 0 N Sam 10512 Wd /fQ-WAM A TTOP/VE 5 5 Dec. 7, 1965 B. w. SCHNEIDER 3,222,032

5 FOLDABLE LIFT DEVICE Filed D60. 23, 1963 2 e ts-s e 2 Fig. 4

ATTO/Q/VEVS United States Patent 3,222,032 FOLDABLE LIFT DEVICE Berthold W. Schneider, Des Moiues, Iowa, assignor to Den-Tal-Ez Chair Manufacturing Co., Des Moiues, Iowa, a corporation of Iowa Filed Dec. 23, 1963, Ser. No. 332,745 8 Claims. (Cl. 254124) The present invention relates to a lift apparatus and more particularly to a jack having foldable lift arms which are raised and lowered by fluid motor means.

It is the object of the present invention to provide an improved lift jack for vertically raising and lowering chairs, such as the contoured dental chair shown in Design Patent No. 186,104.

Another object of the invention is to provide a compact jack having a pair of foldable lift arms which are extended and retracted by fluid cylinder means and wherein a cam slot and cam follower connection between one of the lift arms and the cylinder means acts to stabilize the jack and to provide a lift action along a single vertical line.

A further object of the invention is to provide a jack which is constructed from a minimum number of parts and is foldable into a compact nested relationship.

An additional object of the invention is to provide a durable and eflicient lift jack which is simple and rugged in construction and economical to manufacture.

The exact nature of the invention as well as other objects and advantages thereof will be readily apparent from the consideration of the following specification relating to the annexed drawing in which:

FIG. 1 is a perspective view of the lift device of the invention in the extended position;

FIG. 2 is a reduced sectional view taken along the line 22 of FIG. 1;

FIG. 3 is an enlarged sectional view taken along the line 3-3 of FIG. 2;

FIG. 4 is an enlarged detail view taken along line 44 of FIG. 3 showing the cam and cam follower connection between the cylinder means and lower link or arm of the lift device;

FIG. 5 is an enlarged sectional view showing the lift device of FIG. 1 in the retracted position; and

FIG. 6 is a sectional view taken along the line 66 of FIG. 5.

Referring to the drawing, the lift apparatus 10 of this invention is shown in FIG. 1 in an expanded or raised position. The lift apparatus 10 has a relatively flat elongated base 11 formed with an enlarged circular portion 12 and a rectangular portion 13. Parallel and upwardly projected flanges 14 and 16 are integrally formed with the base portion 13 and extend from the center section of the circular portion 12 along the sides of the rectangular portion 13 and terminate short of the outer end 17 of the rectangular portion 13.

A first channel-shaped lift arm 18 having a flat base 19 and upwardly extended flanges or legs 21 and 22 has a width slightly less than the lateral distance between the flanges 14 and 16 of the base portion 13 so that the first lift arm 18 is movable into a nested relation with the base portion 18 between the flanges 14 and 16. The first lift arm 18 is pivotally connected at one end to the base 11 by means of pins 23 which extend in a transverse direction through adjacent flanges 14 and 21 and 16 and 22 of the base portion 13 and first lift arm 18, respectively.

A second channel-shaped lift arm 24 has a flat base 26 and downwardly extending flanges or legs 27 and 28 spaced apart a distance substantially equal to the space between the base flanges 14 and 16 so as to extend thereover to form a box-shaped structure for receiving the channel-shaped first lift arm 18. The outer ends 29 of 3,222,032 Patented Dec. 7, 1965 the first lift arm flanges 21 and 22 are provided with upwardly extended ears 31 to form a pivotal mounting for the second lift arm 24. Pivot pins 32 extended transversely through the downwardly directed flanges 27 and 28 and the ears 31 pivotally connect the first and second lift arms 18 and 24, respectively.

As shown in FIGS. 1 and 2, the free end 33 of the second lift arm 24 is provided in its base 26 with a rectangular-shaped recess 34 which accommodates a lift pad 36 having a pair of parallel downwardly extended legs 37 and 38. The lift pad 36 is pivotally connected to the second lift arm 24 by a pivot pin 39 which extends transversely through the flanges 27 and 28 and the legs 37 and 38. As shown in FIG. 6, the lift pad 36 is centered in the recess 34 by means of spacers 41 mounted on the pivot pin 39 and positioned between the legs 37 and 38 and the downwardly projected flanges 27 and 28.

The lift pad 36 is maintained in a substantially vertical position during the raising and lowering of the lift apparatus by means including a stabilizing link 42. As shown in FIGS. 1 and 2, the stabilizing link 42 extends substantially parallel to the longitudinal extent of the second lift arm 24 and is connected to a downward extension 43 of the leg 38 by means of a transverse pivot pin 44 and to the outer end 29 of the first lift arm 18 below the ear 31 by means of a transverse pivot pin 46. The stabilizing link 42 and the second lift arm 24 thus form a parallel linkage which horizontally maintains the lift pad 36 for movement in a substantial vertical path.

As shown in FIGS. 1, 2, and 5 the first lift arm 18 is foldable into the base portion 13 and the second lift arm 24 is foldable against the flanges 14 and 16 of the base portion 11 by the action of a fluid motor 47 such as a hydraulic cylinder. The lower end 48 of the cylinder 47 is pivotally mounted to the outer end 17 of the base portion 13 by means of a transverse pin 51 carried in a pair of transversely spaced ears 49 extended upwardly from the base portion 13. The cylinder 47 extends upwardly through a rectangular slot 52 in the base 19 of the first lift arm 18. A piston rod 53 projects from the cylinder 47 and is pivotally mounted at its free end to the mid-section of the base 26 of the second lift arm 24 by means of a pair of downwardly extended spaced ears 54 and a transverse pivot pin 56.

In order to facilitate the assembly and repair of the life apparatus an opening 57 is provided in the base 26 adjacent the ears 54 to permit the insertion and removal of the pin 56.

Cooperating with the parallel linkage of the lift arm 24 and stabilizing link 42 in providing for the vertical movement of the lift pad 36 in a horizontally disposed position are a. pair of guide means 58 and '59 (FIGS. 1 and 4) extended parallel to the flanges 21 and 22 of the lift arm 18 and secured to the base 19 to opposite sides of the cylinder receiving slot 52. Each guide means has a crescent or lunar-shaped cam slot 61. The shape of the slot 61 controls the angular movement of the first lift arm 18 relative to the second lift arm 24 during the raising and lowering thereof by the action of the cylinder 47. A pair of cam followers or rollers 62 are secured to the opposite sides of the fluid cylinder 47 and extend into the cam slots 61 for engagement with the sides thereof.

The cylinder 47 is supplied with a source of fluid pressure by a motor driven pump and reservoir unit 63 (FIG. I) mounted on the base 19 of the first lift arm 18 and connected to the base end of the cylinder 47 by a flexible conduit 64. The motor of the unit 63 is connected by means of suitable switches (not shown) to a v. electric supply 66.

As shown in FIGS. 5 and 6, when the lift apparatus is in its lowered position the second lift arm 24 is folded down against the base 11 so as to rest on the top surfaces of the flanges 14 and 16. The first lift arm 18 and the cylinder 47 and its retracted piston rod 53 are nestedin the closed space between the second lift arm 24 and the base 11. In this retracted position of the piston rod 53 the cam followers 62 are at the forward ends of the cam slots 61.

On energization of the motor driven pump of the unit 63, fluid is supplied to. the base end of the cylinder 47 thereby forcing the piston rod 53 from the cylinder 47. Outward movement of the piston rod 53 rotates the second lift arm 24 about the pivot pins 32. This angular movement rotates the fluid cylinder 47 about the pivot pin 51 in the same direction as the lift arm 24. The angular movement of the cylinder 47 by means of the cam slots 61 in the guide members 58 and 59 and the cam followers 62 therein angularly rotates the first lift arm 18 about the pivot pins 23 in a direction opposite to the angular rotation of the second lift arm 24. When the piston rod 53 is in its extended position the cam followers 62 are seated in the terminal ends 60 of the crescentshaped slot 61, as shown in FIGS. 1 and 2.

The crescent shape of the slots 61 controls the angular movement of the first lift arm 18 relative to the second lift arm 24, which cooperates with the parallel linkage formed by the link 42 and lift arm 24 to maintain the lift pad 36 horizontally disposed with the pivot pin 39 movable in a vertical plane which passes through the pivot pins 23 for the first lift arm 18. When the fluid in the cylinder 47 is released back into the reservoir portion of the unit 63 the first lift arm 18 and second lift arm 24 return to their folded positions shown in FIGS. 5 and 6.

While there have been shown, described, and pointed out the fundamental novel features of the invention as applied to the preferred embodiment, it is to be understood that various changes may be made therein without departing from the scope of the invention as defined in the appended claims.

I claim:

1. A lift apparatus comprising:

(a) base means,

(b) a first lift arm pivotally connected at one end to the base means,

(c) a second lift arm pivotally connected at one end to the other end of the first lift arm,

(d) fluid cylinder means pivotally connected at one end to the base and at the other end to said second'arm means, and

(e) cam and cam follower means interconnecting said first arm means and said fluid cylinder means.

2. A lift apparatus comprising:

(a) an elongated and flat base means having transversely spaced upwardly extended flanges,

(b) a channel-shaped first arm means having a base and lateral flanges extended in an upward direction and spaced transversely a distance apart less than the distance between the flanges on the base means,

(c) means pivotally connecting one end of the flanges of the first arm means on a transverse axis to one end of the flanges on the base to position the first arm means between the flanges of the base,

(d) a channel-shaped second arm means having a base and lateral flanges transversely spaced a distance apart substantially equal to the distance between the flanges on the base means, said second arm means being movable over said base with the flanges thereof extended downwardly and against the flanges on said base,.

(e) means pivotally connecting one end of the second arm means to the other end of the flanges of the first arm means,

(f lift pad means pivotally connected to the other end Of said second arm means,

(g) fluid cylindermeans pivotally connected at one end to the base means adjacent said other end of the first arm means, said cylinder means extended through an opening in said first arm means and pivotally connected at the other end thereof to the mid-section of the base of the second arm means, and

(h) means operatively connected to said cylinder means to supply said cylinder means with a source of fluid pressure whereby said cylinder means expands and retracts to raise and lower said first and second lift arm means.

3. The lift apparatus defined in claim 2 including:

(a) a pair of laterally spaced guide members secured to the base of the first arm means, said guide members extending upwardly and substantially parallel to the flanges of said first arm means, each guide member having a crescent-shaped cam slot, and

(b) roller means pivotally mounted on opposite sides of said fluid cylinder means and extended into the crescent-shaped cam slots of said guide members, said roller means cooperating with said cam slots to control the angular movement of said first arm means relative to said second arm means.

4. A lift apparatus comprising:

(a) base means having transversely spaced upwardly extending flanges,

(b) a channel-shaped first arm means having a base and lateral flanges extended in an upward direction and spaced transversely a distance apart less than the distance between the flanges on the base means.

(0) means pivotally connecting one end of the flanges 0f the first arm means on a transverse axis to one end of the flanges on the base to position the first arm means between the flanges of the base,

(d) a channel-shaped second arm means having a base and lateral flanges transversely spaced 2. distance apart substantially equal to the distance between the flanges on the base means, said second arm means being movable over said base with the flanges thereof extending downwardly and against the flanges on said base,

(e) means pivotally connecting one end of the second arm means to the other end of the first arm means,

(f) lift pad means pivotally connected to the other end of said second arm means,

(g) link means pivotally connected to the lift pad means and to the other. end of the first arm means for maintaining the lift pad means in a vertical position,

(h) fluid cylinder means pivotally connected at one end to the base means adjacent said other end of the first arm means, said cylinder means extended through an opening in said first arm means and pivotally connected at the other end thereof to the mlS-SfiCtiOn of the base of the second arm means, an

(i) means operatively connected to said cylinder means to supply said cylinder means with a source of fluid pressure whereby said cylinder means expands and retracts to raise and lower said first and second lift arm means.

5. The lift apparatus defined in claim 4 including:

(a) a pair of laterally spaced guide members secured to the base of the first arm means, said guide members extending upwardly and substantially parallel to the flanges of said first arm means, each guide member having a crescent-shaped cam slot, and

(b) roller means pivotally mounted on opposite sides of said fluid cylinder means and extended into the crescent-shaped cam slots of said guide members, said roller means cooperating with said cam slots to control the angular movement of said first arm means relative to said second arm means.

6. A lift apparatus comprising:

(a) base means,

(b) a first lift arm means pivotally connected at one end to the base means for angular movement about an exis extended transversely of the base means, the other end of said first lift arm means having a longitudinally extended slot,

() a second lift arm means extended over the first lift arm means and pivotally connected at one end to said other end of said first lift arm means on an axis substantially parallel to the pivotal axis of the first lift arm means,

((1) a fluid motor means pivotally connected at one end to the base and at the opposite end to the second lift arm means, said motor means projecting through said slot in the first lift arm means, and

(e) guide means interconnecting the fluid motor means with the first lift arm means to control the angular movement of the first lift arm means relative to the second lift arm means when the fluid motor is actuated.

7. The lift apparatus defined in claim 6 wherein:

(a) the fluid motor means comprises a cylinder having a piston rod slidably positioned therein, said cylinder being pivoted at one end to said base and said piston rod being pivoted to a mid-section of said second lift arm means, and

(b) the guide means comprises a pair of guide members secured to the first lift arm means adjacent the slot therein, each guide member having a cam surface, and a pair of cam followers secured to the cylinder and engaging said cam surfaces.

8. A lift apparatus comprising:

(a) base means,

(b) a first lift arm means pivotally connected at one end to the base means for angular movement about an axis extended transversely of the base means,

(c) a second lift arm means extended over the first lift arm means and pivotally connected at one end to the other end of said first lift arm means on an axis substantially parallel to said pivotal axis of the first lift arm means,

(d) a fluid motor means pivotally connected at one end to the base and at the opposite end to the second lift arm means, and

(e) guide means interconnecting the fluid motor means with the first lift arm means to control the angular movement of the first lift arm means relative to the second lift arm means when the fluid motor is actuated.

References Cited by the Examiner UNITED STATES PATENTS 2,373,848 4/1945 Owens 254113 WILLIAM FELDMAN, Primary Examiner. 

1. A LIFT APPARATUS COMPRISING: (A) BASE MEANS, (B) A FIRST LIFT ARM PIVOTALLY CONNECTED AT ONE END TO THE BASE MEANS, (C) A SECOND LIFT ARM PIVOTALLY CONNECTED AT ONE END TO THE OTHER END OF THE FIRST LIFT ARM, (D) FLUID CYLINDER MEANS PIVOTALLY CONNECTED AN ONE END TO THE BASE AND AT THE OTHER END TO SAID SECOND ARM MEANS, AND (E) CAM AND CAM FOLLOWER MEANS INTERCONNECTING SAID FIRST ARM MEANS AND SAID FLUID CYLINDER MEANS. 